Circuit interrupter



May 26, 1931. M. sHoENBERG E1' AL 1,806,766

C IRCUIT INTERRUPTER Filed April 13l 1926 mmm W .4 rra/mns Patented May 26, 1931 UNITED STATES PATENT OFFICE MILTON H. SHOENBERG AND LESTER SCHON, 0F SAN FRANCISCO, CALIFORNIA; SAID SCHON ASSIGNOB T0 SAID SHOENBERG CIRCUIT INTERRUPTER Application med April 18,

This invention relates generally to devices for periodicall interruptingA an electrical current. The eatures of novelty have special application in a circuit interrupter adapted to be used as a lamp flasher in conjunction with a lighting circuit.

It is an object of this invention to devise a circuit interrupter in the form of a relatively thin button or disc which may be removably inserted in any lamp socket or receptacle.

It is a further object of this invention to devise a circuit interrupter which will give a uniform flashing period for a given current.

It is a further object of this invention to devise a novel form of mounting for securing an interruptor element within a metallic casmg.

It is a further object of this invention to devise a circuit interrupter which will be rugged in construction but which will have a minimum number of parts and will be cheap to manufacture.

Further objects of the invention will appear from the following description in which We have set forth the preferred embodiment of our invention. It is to be understood that the scope of this invention is to be determined from the appended claims and the state of the prior art.

Referring to the drawings:

Figure 1 is a cross sectional view showing the device applied to a lamp receptacle.

Fig. 2 is a plan view of the device.

Fig. 3 is a plan view showing the mounting for the interruptor elements.

Fig. 4 is a bottom view of the mounting shown in Fig. 3.

Fig. 5 is a cross sectional view taken along the line 5--5 of Fig. 4.

Fig. 6 is a cross sectional view taken along the line 6--6 of Fig. 3.

Fig. 7 is a transverse cross sectional view of the assembled device taken along the line 7-7 of Fig. 2.

Fig. 8 is a circuit diagram showing the connections for the device when employed as a series connected interrupter.

1926. Serial No. 101,675.

Fig. 9 is a circuit diagram of the device showing a shunt form of connection.

Figure 10 is a transverse cross sectional view showing the construction of the bimetal lic interrupter element.

In the past, circuit interrupters for {'lashing lamps were either constructed as a separate element or were built into a lamp socket or receptacle. These devices were inconvenient to use as they necessitated a special electrical installation which in addition to being expensive, could not readily be incorporated with many lamp circuits. In our invention we have constructed a circuit interrupter in the form of a. small button-like unit which may readily be inserted in any lamp socket without making electrical alterations. It is preferably constructed in the form of a relatively flat disc shaped casing which entirely encloses and protects the lnterrupter element. The opposite faces of this casing carry contacts which cooperate with one of the contacts of a lamp socket or receptacle and the end contact of a lamp base.

Thus, as shown in Fig. 1, the device is shown as being in the form of a button-shaped casing 10 which is positioned within a lamp receptacle 11 between the central contact 12 of the receptacle and the central'contact 13 of the lamp 14. The end faces of the casing 10 carry contacts 16 and 17 which make electrical cont-act with contacts` 12 and 13 respectively whereby the interru ter is placed in series with the elements oft e lamp 14. The casing 10 is preferably metallic and constructed of two intertting parts or sections. Thus, as shown in Fig. 7, the casing 10 comprises upper and lower cup-shaped sections 18 and 19 which are adapted to telescope within each other. These sections are preferably insulated from each other so that they may be employed as conductors for the interrupter circuit. Accordingly there is provided an insulating ring 2O which is L-sha ed in cross Y The interrupter element and its mounting are shown more clearly in Figs. 3 to 6 inclusive. The mounting preferably includes a relatively flat member in the form of a disc 24 which is preferably constructed of metal and is provided With a suitable elongated aperture 26, the aperture 26 being offset from the center of the disc for a purpose later to be described. Arranged about the periphery of the disc 24 are a plurality of struck out projections 27 which are normally adapted to engage the section 19 of the casing in order to retain one face of the disc in spaced relationship to the casing section 19. The interrupter element 21 is preferably of the bimetallic type and comprises a bi-metallic element or strip 28 secured at its one end to one face of the disc 24 as by means of an integral upset projection 29. The strip 28 is positioned co-eXtensive with the aperture 26, and so as to operate within the same. The strip 28 is adapted to be flexed by means of a heating resistance coil 30 which is wound about the intermediate portion of the strip. In practice a relatively thin layer of insulating cloth or other ysuitable material 31 is first wrapped upon the stri 28 and then the wire 30 is wound on top o the insulating material 31. The resistance coil 30 is preferably' wound from very fine Wire and is of a suitably high resistance material such as a chromenickel alloy which has a decided temperature resistance coefficient. Its total resistance should be much greater than that of the smallest lamp with which it is adapted to be used. The wire is provided with an enameled insulation and in winding upon the strip 28 the first turns are made directly upon the uninsulated strip 28 so as to form a ground for that end of the coil. The rest of the turns are of course made upon the insulating material 31 and the free end is connected in a manner later to be described. The thickness of the insulating material 31 may be varied to vary thewith a movable contact point 33 of silver,

platinum or other suitable non-oxidizingmetal. This contact 33 cooperates with a relatively stationary contact oint 34 which is mounted -upon the end o the strip 35. The stationary contact preferably has a pointed contact surface as shown in order to facilitate seating the contacts during assembly. The stri 35 is insulated from the disc 24 and is pre erably formed as an integral rojection upon the flat spring stri 36.

-or insulating1 the strip 36 from the d1sc 24 there is provi ed a sheet 37 of suitable insulating material such as mica, which is inserted between the upper face of the disc 24 and the strip 36. The strip 36 and sheet 37 are suitably clamped to the disc 24 by means of an eyelet 38 which projects through apertures in the strip 36 and sheet 37 and through an enlarged aperture 39 in the disc 24. The lower end of the eyelet 38 is insulated from the adjacent face of the disc 24 by suitable means such as an insulating or mica washer 40. To facilitate assembly the upper face of the disc is preferably provided with a plurality of struck up projections 42 which engage in apertures in the sheet 37 whereby the metal eyelet 38 will be accurately positioned within the aperture 39 and will not become grounded upon the disc 24. The free end of the strip 36 is preferably bent upward away from the insulating sheet 37 so as to form a spring contact 43 as shown in Fig. 6.

In Fig. 7 the disc 24 and the interrupter element are shown in assembled relation in the casing 10. The disc 24 is adapted to be grounded upon the casing section 19 while the spring Contact 43 is adapted to make electrical connection with the casing section 18. To facilitate making these connections to the casing and in order to reenforce the casing against collapse, both the upper and lower sections are provided with recessed portions 46 which are further provided with pressed-in projections 47, the projections being adapted to Contact with the center of the lower face of the disc 24 and with the spring contact 43 respectively. The spring contacts 16 and 17 previously referred to are secured to the casing sections 18 and 19 respectively, being preferably mounted upon the recessed ortions 46. These spring contacts are ma e of a metal having high electrical conductivity, such as copper or phosphor bronze, and are each preferably formed of a disc which is split as at 49 along an arcuate line. The inner portion of this disc is then preferably spot welded to the corresponding portion 47 as shown, while the other portion 50 is bent outwardly to form a suitable spring contact.

In order to insulate the casing 10 from possible short circuit with the inclosed portions of the socket or rece tacle, the casing is preferably provided witli a. suitable coating or cover of insulating material. The particular insulating cover shown comprises a pair of interftting cups 52 and 53 which are constructed of suitable insulating material such as bakelite or pyroxyline. These cups are provided with openings 54 to eX ose the contacts 16 and 17 and, after having en placed upon the casing 10, their overlapping flanges are secured together by a suitable cement. In place of using these insulating cups the outer surface of the casing 10 may be coated by a vitreous or other suitable enamel of sufficient thickness to prevent short-circuiting of the casing.

In operation it is preferable to connect the heating resistance 30 in shunt with the contacts 33 and 34 as shown in Fig. 9. When positioned within a lamp receptacle as shown stationary contact 34. Thus, when the contacts 33 and 34 are open, current flows through the heating coil 30 and heats the bimetallic strip 28, thus causing this stri to Vflex and bring the movable contact 33 into electrical contact with the contact 34, thus closing the circuit to the lamp L. Upon closing of the contacts the coil 30 will be shunted out with the result that the bi-metallic strip 28 will be permitted to cool ofl suiiciently to again open the contacts 33 and 34. This operation will be repeated periodically causing the lamp L to flash on and off. The timing of the flashes may be varied somewhat by permanently bending either the strip 28 or the strip 35 to vary the normal distance between the contacts 33 and 34.v It may also be varied by employing dierent thicknesses of insulating material 31 upon which the wire 30 is wound. Since the disc 24 and its inclosing casing are made of metal a substantial heat storage will be formed which will tend to stabilize operation of the interrupter; that is, it will tend tomake the period of the interrupter element more constant. As the Wire in the heating resistance 30 has a relatively high temperature resistance coeflicient, it w1ll have substantially less 'resistance vat the instant when contacts 33 and 34 are broken than when the contacts are closed. In other words, at the instant when the contacts 33 and 34 open, thewire in the coil 30l is at its lowest temperature at which temperature its resistance is relatively low compared to its resistance at the instant when the contacts 33 and 34 close. 'This momentary low resistance of the coil 30 at the instant the contacts open tends to reduce arcing across the contacts and makes possible more rapid operation of the flasher and a higher current carrying capacity. 1

Fig. 8 shows how the device may be modified to operate as a series wound interrupter. In this casaJ one end of the coil 30 is connected to the contact 33 which must of course be insulated from the bi-metallic strip 28. The strip 28 is bent-so thatgthe contacts 33 and 34 are normally closed so that when the lines 1 and 2 are connected as shown, current will initially flow-through the resistance-coil 30 to light the lamp L. Since-the lighting current in this case must flow through the heating coil 30 it is obvious that thiscoil must be made with a relatively low resistance compared to the resistance of the lamp. Upon heating of the bi-metallic element 28 the contacts 33 and 34 are causedv to move apart to interrupt the current in the lamp and the current flowing through the coil 30.

i the other.

,thickness of insulation.

When the heating coil has cooled suiiiciently the contacts 33 and 34 again close.

It will be seen that the above device incorporates several novel features and advantages. Because of its simplicity of construe,- tion it may be readil manufactured in large quantities. Assemb y of the parts is greatly facilitated by retaining the disc 24y within the Casing merely by abutting contacts. Thus, in assembling the device 1t is merely necessary to position the disc 24 with its associated interrupter mechanism within the lower section 19 of thel casing 10. The upper casing section 18 and the insulating ring 20-are then pressed down over the lower section 19 until the projection 47 of the upper section presses down upon the spring contact 43. Thus the disc 24 willl be spring pressed into engagement with the lower casing section. The aperture 26 and interruptor element 28 being mounted to one side of the center of the disc 24 insures suficient clearance to revent short-circuiting of the element 28 against the casing section 19. If the lamp 14 is screwed into the receptacle with more force than necessary, the thrust will be taken by the projections 47 which will engage oppositesides of the disc 24. The operation ofthe device will be independent of weather conditions as the interrupter element is effectively protected from moisture by the housing 10. It will work equally well fora large range of lamps as the resistance of the coil 30 is made relatively high compared to the resistance of the smallest lamp which might be used.

Where itis desired to operate the interrupter element very rapidly, it may be constructed as shown in Fig. 10. In this case the insulating material on the bi-metallic strip 28 is made vthicker on one side than on In other words, the rateof heat transfer from' the coil 30 to the strip 28 is made more rapid on one side than on the other. Thus a sheet of insulating material 131 is Wrapped about the strip 28 with its ends overlapped upon one side to provide a double If the bi-metallic strip is made of layers 128 and 228 ot brass and iron respectively and the overlap is made on the iron side, then the responsewill be rapid providing the iron layer faces the stationary contact 34. However, if `the overlap is on the brass side, or if the bil-metallic element is turned. over with respect to the stationary contact, then the interrupting action will be slow. The' cause for. this action is that the thicker insulation keeps the sides of the bi-metallic strip at different temperatures, thus aiecting the degree of llexure.

It is to be understood that this device is not an adaptor for affecting control of current, but is adapted to be inserted within a lamp socket so that a lamp base or plug may still engage the socket threads.

We claim:

said element.

2. A device of the class described comprising a two part metallic button shaped casing, means for insulating said parts, an interrupter element detachably positioned within said Casin and means for including said two parts o the casing as conductors for said element.

3. A device of the class described adapted to be removably positioned within a lamp receptacle comprising a relatively flat button like metallic casing made of two parts, means for electrically insulating said parts from each other, an interrupter element removably positioned within said casing, and means for including said two parts of the casing as conductors for forming external connections to said element.

4. In a asher button adapted to be removably positioned within a lamp socket, a relatively fiat metallic casing made of two connected ends, means for insulating said ends from each other, and separate contacts secured tothe external faces of said ends.

5. In a fiasher button adapted to be removably positioned Within a lamp socket, a relatively flat metallic casin made of two connected ends, means for insulating said ends from each other, and spring contacts secured to the external faces of said ends.

6. In a device4 adapted to be removably p0- sitioned within a lamp socket, a button shaped casing having closed end faces, a relatively flat member positioned between said faces, and a bi-metallic element mounted on said member.

7. In a device of the class described, a button shapedmetallic casing made of two insulated sections, an interrupter element positioned within said casing, and a mounting for said element comprising a relatively flat metallic member to which said element is secured, and means for spacing said member within the casing whereby said element is retained out of mechanical contact with the inner facesof the casing.

8. In a device of the class described, a relatively flat member having an aperture, a bi-metallic element secured at one of its ends to one face of said member and adapted to operate in said aperture, a contact on `the free end of said element, and a contact secured to the opposite face of said member and adapted to cooperate with said first named contact.

9. In a device of the class described, a relatively fiat metallic member having an aperture oii'set from the center of the same, an interrupter element mounted on said member and having a pair of contacts, and a spring terminal for one of said contacts terminating at the center of one face of the member and insulated from the same, the other of said element contacts being grounded on the metallic member.

10. In a device of the class described, a button shaped casing, an interrupter element positioned within said casing, a member upon which said interrupter is mounted, the faces of said casing having inner projections adapted to contact on opposite sides of said member to prevent collapse of the casing.

11. In a device of the class described, a button shaped casing, an interrupter element positioned within said casing, a disc upon which said element is mounted, peripheral projections on one side of said disc adapted to space the same from one face of the button, and an inner projection on the other face of the button adapted to engage the other face of the disc.

12. A device of the class described adapted to be removably positioned within a lamp socket comprising a button shaped casing formed of two connected sections, an electrical terminal on each of said sections, an interrupter element dis osed within said casing, and a mounting or said element whereby it is retained in operative position and is electrically connected to said terminals only by abutting contacts with the inner walls of the casing.

13. In a circuit interrupter, a pair of relatively movable contacts, a bi-metallic strip, the metals of said strip having dierent coeiicients of expansion and adapted to control said contacts by flexing, a heating resistance disposed about said strip, and means including insulating material of varying thickness between the heating resistance and said strip for e'ecting unequal heating of .opposite sides of said strip.

14. A device adapted to be removablynserted within a lamp vsocket comprising a relatively fiat button-like casing made of sections, contacts carried upon opposite faces of said button, a relatively flat member positioned between said sections, and an interrupter element mounted upon said member, and electricall connected with the contacts, said element eing ada ted to recurrently vary the current supplie by. the socket.

15. A device of the class described adapt'- l ed to be removably positioned within a lamp socket comprising a button shaped casing formed of two connected portions, electrical terminals formed on opposite faces of the casin an interrupter element'within the cas ing a apted to recurrently vary current supplied by the socket, and a mountmg for said element whereby the element is retained in operative position within the casingV and is electrically connected to said terminals only by abutting contacts with the inner walls of the casing.

16. In a circuit controlling device, a casing made of a plurality of sections, contact terminals carried by said casing, a circuit interrupter element, a metallic member serving as a mounting for said interrupter element, a spring contact carried by said member and insulated from direct electrical contact therewith, said mounting being positioned within said casing and retained therein by abutting contacts only, said abuttin contacts serving to operably connect the clrcuit interrupter element to said terminals.

In testimony whereof, we have hereunto set our hands.

MILTON H. SHOENBERG.

LESTER SCHON. 

